1. Field of Invention
The invention relates a control apparatus for controlling a plurality of computers and, in particular, to a control apparatus that controls a plurality of computers through a network.
2. Related Art
A KVM switch refers to a switch that can operate many servers or computers through a set of or many sets of input devices, such as keyboards and mice. With the development of networks, the technique of controlling many servers or computers through a network has become more mature than before. As shown in FIG. 1, a remote computer 100 controls several computers 106 through the network 102, the control apparatus 104 and the KVM switch 108. The remote computer 100 and the control panel 110 can simultaneously control or optionally control the computers 106. The action of the control apparatus 104 is performed after the remote control signal sent out by the remote computer is decoded and transmitted to the computers 106. The control screen is also sent to the remote computer 100 through the control apparatus 104 and the network 102.
The KVM Over IP has its debut in 1999. Most of the original designs collect the RGB signals and keyboard/mouse signals from local computers or the KVM switch using a collector. Afterwards, data conversion and filter processing are performed. After the compression by a compressing chip or computer, the data travel through a local area network (LAN) or wide area network (WAN) to exchange with the remote computer, thus implementing a networking or digitized KVM.
Such techniques usually use computers as the carrier. An application specific standard product (ASSP) is further needed and connected to the computer through a computer interface (e.g. a PCI interface). This design relies the computer to complete the major or most of the processing. Therefore, a corresponding program has to be coded for different operating systems. This makes the computer interface design complicated and renders a higher cost. The KVM Over IP system implemented in this way will become very huge.
Traditionally, the design of separate keyboard/mouse and image processor also increases the cost. Besides, it will be very inconvenient if the keyboard/mouse controller at the near end does not synchronize with the keyboard/mouse controller at the far end, or there is even no local keyboard/mouse controller.
In addition, the traditional way of processing image signals is to transmit data collected by an analog-to-digital converter (ADC) to a memory (usually called a frame buffer), such as SDRAM, DDR, or FIFO. However, the image or video signals usually involve a huge amount of data, converting an RGB signal by the ADC into 15 bits will occupy 30 general-purpose inputs/outputs (GPIO) using a single channel communication to the memory through the field programmable gate array (FPGA) or 60 GPIO's using double channels. This method complicates the circuit design. The wiring on the circuit board is also more complicated, increasing the chip cost. Using too many GPIO's will slow down the chip speed. When sampling and processing image signals at high speeds, the chip is required to be very good. This inevitably increases the cost.
For example, in U.S. Pat. No. 6,304,895, the output of the ADC is received by an FPGA for further output to the SDRAM. The FPGA will use too many GPIO's. Besides, this patent is implemented using a PCI interface. This will result in an over-complicated system that is hard to design.
Therefore, how to provide a controller that does not rely on computer interfaces, reduce the use of GPIO's, and directly process input devices for controlling several computers is a very important issue in the industry.